The present invention relates generally to secondary fluid supply pumps and more particularly to a hydraulically driven, pressure compensated, self-priming, low pressure air or freon supply pump.
In the past, complex and expensive pumps were required to obtain pressure compensated, self-priming, two fluid operation and attempts to make direct pressure-operated reciprocating piston pumps were frustrated by the imcompressibility of hydraulic fluid which would prevent totally bi-stable operation of the free piston.